Journalling means to keep a diary or journal on a consistent basis. It could be a catch-all for your thoughts and ideas across the facets of your life. Alternatively, you can choose to keep a focused research journal, or one that is attuned to your career. It can be private and only for your reference, or you can post your journal online as a tracking and collaborative exercise (many personal blogs started off as online diaries, remember?). Journalling is very different from the craze of 'bullet journaling', a.k.a. 'bujo', which leans much more towards the productivity/to-do list end of things.